978 Transactions of the American Institute. 



through the hands of Mr. Anthony, for the collection belonging to 

 the Section. 



The Chairmam, in speaking of Mr. C. Wager Hull's recent article, 

 published in the Philadelphia Photographer, upon " The Retarding 

 Influence of Albumen when used as a Substratum in the Preparation 

 of Dry Plates," remarked that Mr. D. Chapman had, at a meeting of 

 this Society, held some years ago, called attention to the fact, the age 

 of the albumen had great influence upon its action, in regard to 

 sensitiveness, when so used. In his own recent experiments, he had 

 used a sample of very old crystallized albumen, a solution of which 

 he had applied, with a brush, in a line one-half inch wide, extending 

 entirely around the edge through the entire length and breadth of the 

 plate, and crossing at right angles in the center. A plate so treated, 

 and upon which a negative had been made, was exhibited before the 

 Section ; it did not appear to have been in any way affected by the 

 albumen so applied. 



Mr. O. G. Mason said that, after reading Mr. Hull's article, he 

 made a series of experiments with plain albumen, and also with albu- 

 men to which a trace of ammonia had been added. Mr. Hull's state- 

 ment, that albumen, to which he always adds ammonia, increased the 

 intensity in wet plates and retarded it in dry plates, having led him, 

 Mr. M., to suppose that possibly a trace of the ammonia was liberated 

 from the dried albumen and became incorporated with the collodion 

 film during the exposure of the wet plates, which condition did not 

 exist in the dry film. In the few experiments which he had made, 

 the plain albumen seemed to be slightly preferable in point of sensi- 

 tiveness. 



Mr. II. J. Newton gave the following formula for developing 

 plates prepared by Blair's Gum Tannin process : "Water, one ounce ; 

 tannin, six grains; pyrogallic acid, six grains ; ammonia, two drops ; 

 acetic acid, sufficient to clear the solution. 



Mr. H. T. Anthony remarked that he had prepared very fine dry 

 plates for transferring with Mr. Anthony's bromo-iodized collodion, 

 to each of which one drop of iodide of iron had been added, sensi- 

 tized in a bath rendered acid by acetic acid ; after which the plates 

 were well washed and flowed with a two-grain solution of phosphate 

 of soda ; then washed again and flowed with a two-grain solution of 

 gallic acid. They were printed by contact, and developed with a 

 one-grain solution of pyrogallic acid, a twenty-grain solution of citric 

 acid, and a ten-grain silver solution and toned with gold. He stated 

 that a very sensitive solution for solar camera printing could be pre- 



